Various "incapacitating" projectiles are known for use in order-maintaining operations. They are of various shapes, being spherical or rod-shaped, and they act by the effect of the impact that occurs on kinetic energy being transformed when contact is made with the target. Whatever their caliber (12-bore, i.e. 18 mm, or 35 mm, 37 mm, 38 mm, 44 mm, and 56 mm), these projectiles all share the characteristics of being light in weight and of moving at high velocity, with their deformability at the moment of impact remaining rather relative, and in nearly all cases depending on the elastic qualities of the materials used.
In other known projectiles, the looked-for objectives are to obtain a soft impact effect or to disperse a liquid or a powder on a target person.
These high velocities are associated with the fact that in order to obtain good accuracy and a sufficiently large impact effect, on the basis of criteria concerning the energy of the round, its muzzle velocity from a launcher must be high. The mass of the projectile that is put into motion is small, so a large propellant charge is required to obtain proper combustion and firing that is regular. Such rounds therefore operate in a manner that is similar to that of conventional projectiles. The surfaces of such projectiles need to be relatively rigid in order to avoid any in-flight deformation which could spoil accuracy at such velocities.
Because of this rigidity and because of the high elastic qualities of the round, its impact area remains much the same as the area of its initial caliber. In addition, since the impact is pseudo-elastic, a portion of the energy E=1/2MV.sup.2 of the projectile is lost in rebound and in heat of deformation. This point is particularly true when the target has a hard portion. To mitigate this drawback, manufacturers propose "spring" type mechanisms for breaking into a plurality of portions or for stretching, which mechanisms are indirect ways of consuming energy to prevent rebound and to lengthen the duration of impact so as to come closer to the effect of a soft impact.
Fragmentation is to be avoided, not only because it departs from soft impact, but also because it can give rise to severe localized lesions.
Although the energy that is, in fact, dissipated in the target is an essential criterion, that assumes that the impact can be thought of as a soft impact in which all of the momentum Q=MV is uniformly transferred from the projectile to the target. To do this, it is necessary for the projectile to be very highly deformable on impact and for it to have minimum elasticity on the impact axis so as to avoid any rebound.